Generally, a measuring tape having a tape configuration with length-indicating markings formed on a surface thereof is used for measuring widths or breadths of a certain space, or for measuring sizes, lengths or widths of a measured object.
While there are several forms of measuring tapes available, a typical example will be a measuring tape that includes a ruler wound in a coil shape with markings formed on a surface, an inner space for accommodating the ruler, and a case having an entrance through which the ruler is extended out of the inner space and retracted back into the inner space. In order to measure a length of the measured object, an operator pulls out the ruler with markings indicated thereon and read the markings on one end and a body portion of the ruler when the ruler reaches an end of the measured object.
However, while the conventional measuring tape is capable of measuring straight lengths of a measured object, it has a difficulty of measuring circumference of a cylinder or curved lengths as it is not in a freely bendable form.
Another conventional measuring tape is freely bendable and thus capable of measuring both the straight lengths and the curved lengths. However, this type of measuring tape is not able to measure a long length accurately because the tape bends when measuring the long length.
Moreover, because an operator of the conventional measuring tape manually measures lengths and checks the measurements himself or herself, errors may be generated depending on operators, and the operator has inconvenience of having to measure the lengths and then record the measured numbers with handwriting or separate typewriting.
Meanwhile, an electronic tape measure has been developed, which electronically measures the length of the ruler extended outside. This electronic measuring tape uses a method of forming holes in the tape or a rotator and irradiating a laser to sense a degree of extension of the tape (i.e., photo interrupter). However, the photo-interrupter method described above is not suitable for use in a place such as construction site where dusts are prevalent, and there also is a problem that the length measuring resolution is limited to intervals between the holes.